Last night, I was reading Qian Zhongshu's Humans, Beasts, and Ghosts. The English translation includes his essays, originally published as Written in the Margins of Life. In these essays, with deceptive titles such as "Windows" or "A Prejudice," Qian would take a point he had mused on at some point while reading some work and he would compose an essay that would take that work as a starting place for his own exploration into issues such as what constitutes happiness or what value does a "moral reading" of a text have. In some regards, he is a spiritual kin to the 16th French essayist Montaigne, whose Essays, or attempts at describing the world/life around him, altered the very meaning of the word "essay" in English.
When I prepare to do a review, I still utilize a method similar to what I have photocopied below from my preserved notes for my graduate thesis on Adolf Hitler's complex relationship with the Christian faith(s). Nearly seventeen years after I first began my research in late 1995 and continuing through the fall semester of 1997, I find that these own modified marginalia provide a snapshot not only into my former professional life, but also in how I still sometimes go about the business of writing a review. Although I no longer am as detailed in my notes (for fiction, I generally just write down a page number, knowing that I will be selecting a quote from there for discussion, while for non-fiction, I do sometimes write this way), there certainly are patterns that can be seen from this. Not just in how I go about reading a book, but how I plan for re-reading it. Look at the questions I ask of the text and the occasional commentaries (some of them actual true marginalia!). I recorded not just my impressions of the texts (Werner Maser's biography on Hitler, August Kubizek's memoirs, Otto Wagener's quasi-diary/memoirs), but I also began shaping the narrative for interpreting them when I would inevitably revisit those pages.
Yet marginalia by itself is of little value unless the writer/reader reacts against it, tests it, probes to create a synthesis that combines the author's writings with the reader's reactions and questions. Sometimes, as in the case of the Qian Zhongshu book I mentioned above, the result is something that is so profound that even hoary old fictions like Aesop's fables can be examined in a different light. Perhaps that is why we engage in marginalia on occasion, as reading can be something that is much less passive than its detractors (or even its erstwhile supporters) ever want to acknowledge. And while some marginalia, such as the examples I provided above, likely won't be of general interest, even private reconsideration of texts can lead to productivity in terms of what the reader takes away from the text with which s/he has been engaged for some time.